Satellite tracking identifies risk zones for leatherback turtles

The last large populations of the leatherback turtle are at risk because their migratory routes in the Atlantic Ocean converge with the locations of industrial fisheries, a new study shows.

Researchers used data from satellite transmitters attached to turtles to track their movement across the Atlantic Ocean. These movements were overlapped with information on high pressure fishing areas to identify where the turtles are most susceptible to entanglement and drowning.

The international study, jointly led by Dr Matthew Witt of the University of Exeter and Dr Sabrina Fossette of Swansea University, found that urgent international efforts are needed to protect the iconic species. Laurent Kelle, Aimée Leslie and Sebastian Verhage of WWF co-authored the report.

Between 1995 and 2010, a total of 106 leatherback turtles were tracked by satellite in the Atlantic and southwest Indian Oceans. The information was interpreted along with knowledge of longline fishing efforts, resulting in the identification of nine areas with the highest risk of bycatch.

Maps of the daily locations of the turtles revealed that Atlantic leatherbacks use both deep sea international waters (more than 200 nautical miles from land) and coastal national waters, either seasonally or year-round, in a complex pattern of habitat use.

More than 4 billion hooks – equivalent to 730,000 hooks per day – were set throughout the entire Atlantic Ocean by industrial fisheries between 1995 and 2010, the study shows.

“This study demonstrates the need to take action at a regional policy level,” said Aimée Leslie, global cetacean and marine turtle programme manager of WWF International. “The International Commission for the Conservation of Atlantic Tuna (ICCAT) has a unique opportunity to use this data to assess the impacts of fisheries under their watch.”

The study results from the collaborative efforts of ten data providers that have tracked leatherback turtles in the Atlantic Ocean since 1995 through the Trans-Atlantic Leatherback Conservation Initiative (TALCIN), a WWF led initiative.

“The TALCIN initiative will continue to build on this work by reaching out to collaborate with organisations such as ICCAT to help assess the level of damage on Atlantic leatherbacks and other marine turtles,” said Leslie. “We will also work with a collaborative fisheries research fellow from the Virginia Marine Institute to find solutions to the threats these species face. The time to act is now.”

The article, ‘Pan-Atlantic analysis of the overlap of a highly migratory species, the leatherback turtle, with pelagic longline fisheries,’ is published in Proceedings of the Royal Society B.